This lecture reviews the environmental factors affecting the aluminium industry and the remedial practices followed; it describes the concept of a product life cycle and the importance of recycling; it also describes the secondary aluminium industry, its history, processes, products and structure; it outlines the methodology used to calculate recycling rates and summarizes the scope and size of the European aluminium industry.

1. TALAT Lecture 1102
Environmental Factors
16 pages, 14 figures
Basic Level
prepared by Geoff Budd, Aluminium Federation, Birmingham
Objectives:
− to appreciate the importance of aluminium application technologies
− to aquire a basic knowledge of a major materials industry and the products
available to manufacturing industry
More specifically, the objectives are
− to review the environmental factors affecting the aluminium industry and the
remedial practices followed
− to describe the concept of a product life cycle and the importance of recycling
− to describe the secondary aluminium industry, its history, processes, products and
structure. To outline the methodology used to calculate recycling rates.
− to summarize the scope and size of the European aluminium industry.
Prerequisites: None
Date of Issue: 1994
 EAA - European Aluminium Association

2. 1102 Environmental Factors
Table of Contents
1102.01 Industry and the Environment................................................................... 3
Ecological Concern ...................................................................................................3
Best Available Technology (BAT)............................................................................4
Aluminium Industry and the Environment................................................................5
- Bauxite Mining ................................................................................................... 5
- Alumina Production............................................................................................ 6
- Electrolysis ......................................................................................................... 6
1102.02 Product Life Cycle ....................................................................................... 8
Environment Protection by Energy Saving ...............................................................8
Improvements in Production Techniques................................................................10
Energy Content Reduction and Recycling Rate ......................................................10
1102.03 Secondary Aluminium............................................................................. 12
New and Old Scrap .................................................................................................12
Processing of Scrap .................................................................................................12
1102.04 Secondary Aluminium Industry............................................................. 14
The Products............................................................................................................14
Structure of the Secondary Industry ........................................................................15
Recycling Rates.......................................................................................................15
1102.05 List of Figures ............................................................................................ 16
TALAT 1102 2

3. 1102.01 Industry and the Environment
• Ecological Concern
• Best available technology (BAT)
• Aluminium industry and the environment
− Bauxite mining
− Alumina production
− Electrolysis
Ecological Concern
Environmental awareness is largely a feature of the last half of this century. Widespread
debates were common in the 1960s but most of the problems caused by man's
insensitivity to his environment remained unsolved or indeed undiscovered. Smoke and
industrial fog was tackled in several countries with dramatic effects (see also Figure
1102.01.01).
90's: GLOBAL
80's: REGIONAL
RAW MATERIALS
70's: LOCAL
ENERGY
DISCHARGES TO
SOIL AND WATER
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Source: B. E. Dahlberg. 1991
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Training in Aluminium Application Technologies
Environmental Awareness 1102.01.01
In the 1970s most attention was focused on the local plant with various industrial
cleaning systems being introduced. Inside the factory a great deal was achieved to
improve working conditions and in the protection of the workers themselves.
In the '80s these concerns became regional. The acid rain debate for example dates from
that decade.
Currently the centre of attention are the global consequences of industrial activity.The
destruction of the tropical rain forest, the depletion of the ozone layer and the
greenhouse effect are of international concern.
TALAT 1102 3

4. In all these stages of opinion development the aluminium industry has usually kept
somewhat ahead of the rest of basic manufacturing industry.
There is increasing concern that we utilise all natural resources in a way to ensure
sustainable growth. The reclamation and reuse of materials instead of dumping them has
become an attractive, and in some cases an economic option. Waste, both domestic and
industrial, is an increasing problem and of great public concern.
Best Available Technology (BAT)
Politics follows opinion, so laws have been proposed giving the producers of materials
and products extended responsibilities after they have reached the consumer, and in
some cases even after they have been finally discarded (Figure 1102.01.02).
FABRICATION END PRODUCT CONSUMER
RECYCLING
Source: B. E. Dahlberg, 1991
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Global Consequences 1102.01.02
Training in Aluminium Application Technologies
The effect of market forces in the environmental field should not be underestimated.
Effluents and waste almost always involve the loss of valuable raw materials and
energy. Pre-dating the ecology debate by many decades simple self interest achieved
real progress.
These rudimentary pressures led to the concept of the ″best available technology″ (BAT)
which remains the most effective tool in this environmentally aware age. The best
available technology may not suit the idealist. Critics should, however, take into account
the costs of remedial or preventive action and the effect on international
competitiveness.
Such a concept (BAT) clearly requires an historical perspective when judging the
performance of a plant at a specific time. What was the BAT when the plant was built
and are more recent innovations of the "bolt on" variety or can they only be applied to a
green field site?
TALAT 1102 4

5. Aluminium Industry and the Environment
Whilst this is not the place for detailed consideration of all possible negative, or, indeed,
positive ecological effects, it is possible to summarise the position in the main sectors of
the aluminium industry.
- Bauxite Mining
The main potential problems with bauxite mining are the effects of deforestation (see
Figure 1102.01.03).
PROBLEM EFFECT BAT
BAUXITE MINING.
Deforestation Regional climate Planned reinstatement
changes
Soil erosion Topsoil loss ---- " ----
ALUMINA PRODUCTION
SO 2 Acid rain Exhaust neutralisation
CO 2 Global warming Improved combustion efficiencies
Dust Inconvenience Better handling to minimise Al 2 O3 loss
Red mud Loss of land use "Dry stacking"
during settling
period
Caustic leach Improved recovery of
process NaOH
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Ecological Considerations. 1. 1102.01.03
Training in Aluminium Application Technologies
A commercially viable deposit will take a minimum of five years to work to exhaustion
of the ore. Mining begins with the removal and storage of the topsoil and overburden on
the first area to be worked. At this initial stage seed is collected from the indigenous
plants and trees for the propagation of seedlings.
As soon as mining has progressed sufficiently reinstatement can commence. The vast
majority of mining areas, over 90%, are restored to the original land use, i.e mining area
reinstatement currently shows 80% restored indigenous forest or scrubland, 11% to
agriculture and pasture, 7% to commercial forest and 2% to industrial and recreational
use. What use is made of restored areas is usually the prerogative of the host country.
Reinstatement will usually be complete within 2 to 3 years of the cessation of mining on
the site.
TALAT 1102 5

6. - Alumina Production
The production of alumina from bauxite is a chemical process involving caustic soda
and appreciable process heat. The effects of the generation of heat are common to all
combustion processes such as electrical power generation from coal or oil and the
possible remedies are the same.
The largest amount of heat is used to drive off the chemically combined water in
aluminium hydrate at the final stage of producing alumina. Substantial economies have
been achieved in modern alumina plants by using fluid bed furnaces instead of the
traditional revolving cylindrical kiln.
The red mud residue could provide an ideal material for brick making. Alas most
alumina plants are located in areas where the demand for bricks is very limited. Bricks
are of course heavy and uneconomical to transport long distances. Dry stacking greatly
reduces the area required for storage, minimises the time lag before site restoration and
largely eliminates caustic leach.
- Electrolysis
The electrolytic process again gives rise to some of the same problems with the same
complete or partial remedies. Fluorides, PAH and dross do require comment (see
Figure 1102.01.04).
PROBLEM EFFECT BAT
ELECTROLYSIS
Fluoride Effect on cattle Containment of cells & dry scrubbing of
emission and vegetation extracted air to return fluoride to the
process
Dust Inconvenience Better alumina handling
Polycyclic Can cause cancer Fume collection & treatment in
aromatic carbon plant
hydro carbon
(PAH)
CO2 /CO Global warming As for alumina
SO2 Acid rain ---- " ----
Dross Noxious fumes High temperature dross treatment (which
also recovers extra usable Al)
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Ecological Considerations. 2. 1102.01.04
Training in Aluminium Application Technologies
The first two need site monitoring before the smelter is built to establish prevailing
levels - either from natural causes or the then existing environment. Since the lead time
from concept to commissioning can be five to ten years this can be done. Monitoring
will be continued for the entire life of the plant.
TALAT 1102 6

7. The dry scrubbing process involves the use of fresh alumina being used as the active
filter material. It is periodically renewed with the used alumina being fed into the pot
lines thus returning the fluoride to the process.
The dross treatment is highly effective. Indeed, merely covering hot dross in airtight
conditions will eliminate the very acrid smell.
These problems have different impacts on the working environmental, local community,
regionally and globally. For example, the CO2, CO and SO2 contribution by the
aluminium industry is infinitesimal in global terms but possibly measurable at a local
plant level.
A state of the art new plant will beat existing standards and will steadily improve by fine
tuning and feasible new BAT application. A further quantum leap in efficiencies and
emission control may have to wait until the end of the plant's economic life.
Progress in these areas is measurable and a good example can be found in the reduction
of fluoride emissions from Norwegian smelters (Figure 1102.01.05).
Norwegian Aluminium Smelters' production and
emission of fluorides to the atmosphere 1960-90
Specific emission of Collective emission of Produced aluminium
fluorides to the atmosphere fluorides to the atmosphere
Kg F per t. aluminium 1000 tonnes F per year 1000 tonnes per year
5.40 4.40 2.20 0.89 2.24 1.48 0.66 165 510 673 870
0.76
1960 1970 1980 1990 1960 1970 1980 1990 1960 1970 1980 1990
Source: B. E. Dahlberg, 1991
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Fluorides to the Atmosphere 1102.01.05
Training in Aluminium Application Technologies
The specific emission has decreased from 5.4 kg to 0.7 kg per tonne of metal produced.
The total emissions are substantially lower today than 30 years ago, even though the
production of primary aluminium is five to six times greater.
The main semi-fabrication processes used by the industry are very similar to those used
with other metals and thus the problems caused and the effective solutions are similar.
TALAT 1102 7

8. 1102.02 Product Life Cycle
• Environment protection by energy saving
• Improvements in production techniques
• Energy content reduction and recycling rate
Environment Protection by Energy Saving
The ecological and environmental story cannot end with the semifabricated product, it
must be followed into the life service of the consumer end product. Different products
have very different life spans, a beverage can might last six weeks from filling to trash
can, an aluminium window perhaps 60 or more years and the aluminium components in
an automobile probably 10/12 years.
During the product service life aluminium will provide various savings: energy related if
the end product is mobile and maintenance savings in the case of the window - say ten
coats of paint and the labour to apply them. In packaging the savings would be in
increased shelf life, lower spoilage or some similar measure.
The energy saving by using lightweight aluminium in transport applications can be
considerable (see Figure 1102.02.01). Total net energy savings over a railcar’s service
life can exceed 1 million KWh, with the aluminium content then available for recycling.
This simplified calculation demonstrates how replacing heavier materials with
aluminium in a metro carriage results in reduced energy consumption. After allowing
for the energy content of the carriage constructional materials overall savings are
achieved in some 3 years.
Aluminium in metro carriage
Energy consumption,
MWh steel carriage
(9.5 tons)
100 Assumptions:
80% recycling
of materials Energy consumption
Al production : 40 MWh/ton
No recycling
50 of materials Energy consumption
Steel production : 10 MWh/ton
1y 2y 3y 4y
0
Distance driven : 115,000 km/year
Energy savings each Distance between
-50 year for metro due to stations : 1.2 km
reduced fuel
consumption Maximum speed : 75 km/hour
-100 Acceleration : 0.92 m/s²
Retardation : 1.03 m/s²
Energy consumption
-150 aluminium carriage alu
(4 tons)
Source: B. Viig
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Energy Calculations 1102.02.01
Training in Aluminium Application Technologies
TALAT 1102 8

9. A metro carriage probably has a service life of 30/40 years. Energy savings can of
course be roughly equated with reduced pollution as less energy means less fuel burnt in
the vehicle's engine, or at the electricity generating station.
This example illustrates the proportionate reduction of emissions as a result of reduced
fuel consumption in an automobile, leading to an overall reduction in emissions in only
a few years. The additional energy content of the aluminium is based on the western
world average (i.e. approximately 60% hydro-power) to provide the CO2 figure (Figure
1102.02.02).
100 kg Aluminium in car
CO2
Western world average
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Year
CO2 -curve for western world average
power sources
Source: B. Viig
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CO2 Calculation Example 1102.02.02
Training in Aluminium Application Technologies
The energy breakeven point sees the start of a global benefit. The car user makes
savings from day 1 of his or her ownership (Figure 1102.02.03)! The USA currently
requires new cars to exceed 33 miles per gallon, a figure that may be raised to 40.
Weight reduction is the most straight forward way of achieving this - unless passengers
get much smaller.
Km/litre
12
11
Engine downsized proportionately.
Car dimensions remain constant,
10 lighter version uses aluminium body
shell and engine components.
9
8
WEIGHT IN Kg 910 1365
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Training in Aluminium Application Technologies
Lower Weight = Less Fuel Consumption 1102.02.03
TALAT 1102 9

10. Improvements in Production Techniques
The service life story cannot be complete without mentioning the benefits provided by
the steady improvement in production techniques within the semi-fabricated product
sector.
The ability to tighten tolerances, to roll or extrude thinner material and maximise
physical properties have lead to "down gauging". For example this has allowed an
increase in the number of beverage cans produced from a tonne of metal to increase by
some 15% over a relatively short period. Intricate architectural extrusions have shown
similar improvement. The gauge of foil has been progressively reduced, without loss of
properties, by closer rolling control and minor alloy adjustment.
This type of improvement has been encouraged not only by competition from alternative
materials but by competition within the aluminium industry.
Energy Content Reduction and Recycling Rate
No service life history can be complete without consideration of what happens at the
end of a product’s useful life. With aluminium products the high scrap value plays a
deciding role at this point (Figure 1102.02.04).
Automotive scrap
Aluminum: $700 per tonne
Rubber: $260 per tonne
Steel: $100 per tonne
Glass: no market
Plastic: no market
1991 US prices.
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Training in Aluminium Application Technologies
Value of Recyclable Materials 1102.02.04
Aluminium's potential for recycling is virtually inexhaustible and only some 5 per cent
of the energy needed in primary production is required to produce equally usable metal.
Hence the relatively high value of aluminium scrap.
If the scrap return rate on a product reaches 90 per cent, the energy required to produce
new products would be around 15 per cent of that required for products made entirely
TALAT 1102 10

11. from primary metal (Figure 1102.02.05). That level of performance has been
approached in several countries in the case of cast automobile components.
When energy savings through recycling compound the reductions made by light-
weighting, the time to realize net energy savings is substantially reduced. This effect
was indicated on the metro carriage example (Figure 1102.02.01).
100
80
60
ENERGY
RECYCLED AL.
ENERGY
%
CONSUMED
40 PRIMARY AL.
20
0
0 10 20 30 40 50 60 70 80 90 100
AMOUNT OF RECYCLED ALUMINIUM %
Energy Consumption for the Production of Secondary
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1102.02.05
Training in Aluminium Application Technologies Aluminium Depending on the Recycling Rate
The process (new) scrap generated within the aluminium industry from smelting to
semi-fabrication has always been recovered 100 per cent and frequently re-processed
within the same plant.
A similar recovery is achieved by large users of their process scrap.
TALAT 1102 11

12. 1102.03 Secondary Aluminium
• New and old scrap
• Processing of scrap
New and Old Scrap
Aluminium has been recycled since the earliest days of commercial use. A published
reference to the economic advantage has been found dated 1903 concerning domestic
utensils. A large number of secondary refiners have been established, converting new
and old aluminium scrap into foundry ingots (casting alloys), deoxidiser for the steel
industry and into wrought alloy slabs and billets.
A wide variety of scrap is processed. New scrap is that surplus material that arises
during the manufacture and fabrication of aluminium alloys up to the point where they
are sold to the final user. Thus extrusion discards, sheet edge trim, turnings and millings
and drosses could all be described as new scrap. On the other hand, old scrap is
aluminium material that is recovered when an aluminium article has been produced,
used and finally discarded. Such scrap could be a used beverage can, a car cylinder head,
window frames from a demolished building or old electrical conductors.
Most new scrap reaching the secondary industry comes directly from the fabricators. It
is usually of known quality and composition and often uncoated. It can then be melted
down with little preparation, apart perhaps from baling.
Old scrap comes via a very efficient network of metal merchants who have the
technology to recover aluminium from motor vehicles, household appliances etc. This is
often done using heavy equipment such as shredders together with magnetic separators
to remove iron and sink-and-float installations to separate the aluminium from other
materials.
Processing of Scrap
Both types of scrap are processed prior to melting to suit any contamination that may be
present. Turnings and millings usually contain oil, water and iron. They are centrifuged
and dried to remove the oil and water and then magnetically separated from the iron.
Used beverage cans are processed to remove the interior lacquer coating and the outside
product display printing inks. This reduces fume emissions and gives pre-heating energy
prior to re-melting.
TALAT 1102 12

13. Several melting processes are used depending on the scrap quality (Figure 1102.03.01).
Clean, uncoated scrap can be melted in a reverberatory furnace (see Figure 1102.03.02);
finely divided scrap, such as turnings, are ideally melted in a coreless induction furnace;
contaminated lower grades of scrap are melted under a flux cover in a rotary furnace
(see Figure 1102.03.03) and scrap components contaminated with other metals such as
steel bolts or studs can be melted in a sloping hearth furnace.
BURNERS
CHARGING
SCRAP DOOR
ALUMINIUM
WELL
Secondary Aluminium:
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Training in Aluminium Application Technologies
Sloping Hearth Furnace alu
1102.03.01
Molten metal fluxing and filtration has been developed to produce aluminium alloys of
the desired composition and quality without undue impact on the environment. Most
modern secondary aluminium melting furnaces are fitted with fabric filters to ensure
that flue gases have a minimal dust content.
BURNER
WELL
ALUMINIUM
NON-WETTING BRICK alu
Secondary Aluminium:
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Open Well Reverberatory Furnace
1102.03.02
Training in Aluminium Application Technologies
TALAT 1102 13

14. STEEL TYRE
BURNER
FLUX
CHARGING DOOR ALUMINIUM
ROLLER DRIVE
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Secondary Aluminium: Rotary Furnace 1102.03.03
Training in Aluminium Application Technologies
1102.04 Secondary Aluminium Industry
• The products
• Structure of the secondary industry
• Recycling rates
The Products
Secondary aluminium refiners convert most of their materials into foundry ingot,
generally based on the aluminium-silicon alloy system with additions of other metals
such as copper and magnesium. These ingots, to recognised national or international
specifications, go into the manufacture of aluminium cast components. Some of this
metal is delivered in a molten form by road tanker to large foundry users thus
eliminating a further remelting operation.
Deoxidiser for the steel industry is supplied in notched bar or granular forms.
Alloy "hardeners" are also produced. These ingots, with a high known percentage
content of alloying metals, are used by other sectors of the aluminium industry such as
primary smelters and wrought remelts.
The reprocessing of used beverage cans (UBCs) is a specialist branch of the industry.
Here UBCs are dealt with in a dedicated facility and the end product is rolling ingot
ready to be reprocessed into can body stock. A modern plant of this kind will treat some
TALAT 1102 14

15. 50,000 tonnes of UBCs per year (see Figure 1102.04.01); there are between 40 and
50,000 UBCs to the tonne.
MELTING FURNACES
SHREDDER
FEED
DECOATER MAGNETIC
SEPARATOR
DEGASSER DIRECT CHILL
CASTING UNIT INGOTS
TILTING HOLDING FILTRATION
FURNACE
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Beverage Can Recycling Plant 1102.04.01
Training in Aluminium Application Technologies
Until the can market and the UBC recovery infra-structure has developed to a sufficient
size such plants are not a viable proposition. There is at present only one such plant
within Western Europe.
Structure of the Secondary Industry
Secondary aluminium refiners may be integrated into major aluminium companies or
they may be entrepreneurial, independent companies. Because of the rapidly changing
price of aluminium scrap and primary metal and the fluctuating market for foundry
alloys, the refiners need to be very flexible in both buying and selling.
Some countries generate more scrap than the national foundry industries can absorb.
The secondary refiners in these cases need to sell internationally.
Recycling Rates
It has already been noted that new aluminium scrap, being readily identified and within
the control of the industry, has a recycling rate of virtually 100%.
The recycling of old scrap is more interesting and depends on the basis used for
calculating the percentage rate for various types of scrap. Should the recovery of
aluminium scrap from automobiles be measured against shipments of foundry metal to
automobile component suppliers during the current year or, since the average life of a
car is 10/12 years, shipments made 10 years ago?
TALAT 1102 15

16. The secondary industry calculates that 63% of available scrap is recovered. Within
Europe there are some 200 such companies who in aggregate ship some 1.7 million
tonnes of secondary products each year.
Many materials have a very high recycling rate; aluminium printing plates and
automobile castings being good examples. The recovery of UBCs varies according to
the national recycling infra-structure and within Europe varies from a few per cent to as
high as 80%. The UK for example with rapidly growing UBC recovery systems expects
to reach 50% by 1996.
The values for other types of packaging are not so good, largely because material such
as foil is thinly spread throughout the population.The problem is one of recovery rather
than technology.
1102.05 List of Figures
Figure No. Figure Title (Overhead)
1102.01.01 Environmental Awareness
1102.01.02 Global Consequences
1102.01.03 Ecological Considerations 1
1102.01.04 Ecological Considerations 2
1102.01.05 Emission of Fluorides in Relation to Aluminium Production
1102.02.01 Energy Calculations: Aluminium in Metro Carriage
1102.02.02 CO2 Calculation Example
1102.02.03 Lower Weight = Less Fuel Consumption
1102.02.04 Value of Recyclable Materials
1102.02.05 Energy Consumption for the Production of Secondary Aluminium
depending on the Recycling Rate
1102.03.01 Secondary Aluminium: Sloping Hearth Furnace
1102.03.02 Secondary Aluminium: Open Well Reverberatory Furnace
1102.03.03 Secondary Aluminium: Rotary Furnace
1102.04.01 Beverage Can Recycling Plant
TALAT 1102 16